Frequently Asked Questions at the CSO 

1. What is submillimeter? What is submillimeter astronomy?

The word ‘submillimeter’ refers to the wavelength of electromagnetic wave detected by this telescope.  The size range of the wavelength is less than one millimeter (approximately 1/25 inch) and longer than 100 micron (1/250 inch).  The submillimeter region of the electromagnetic spectrum is at the border between the far infrared and the short-wavelength radio regions. As such, it borrows technologies from both regimes: bolometers from the infrared, heterodyne receivers from the radio.  Water vapor in the Earth’s atmosphere strongly absorbs these radiations so that submillimeter telescopes need to be located at very dry places such as on high mountains or on the Antarctic plateau (for example, AST/RO is a submillimeter telescope at South Pole).  The transparency of the atmosphere to submillimeter radiation is shown here.  Note that the wavelength 1mm corresponds to 300 GHz and 300 micron corresponds to 1000 GHz (1 THz), respectively.  At Mauna Kea, precipitable water vapor (sometimes called PWV) under good observing weather is less than 1 mm.  The ability to detect such submillimeter waves have been developed only in recent decades. This, combined with the need for a high-altitude site, has resulted in submillimeter astronomy being among one of the newest and least studied areas of astronomy.  Submillimeter radiations are generated in very cold, dusty regions of space, which are the targets of broad astronomy fields, such as star formation, interstellar medium, planetary systems, evolved stars, evolution of galaxies, and cosmology.  Astronomers have special interest in this wavelength, and many important studies remain to be done.

2. When was the telescope built?

 The CSO 10.4m telescope was completed and started operation at the top of Mauna Kea in 1986.

3. Who built the telescope?

The CSO 10.4m telescope was designed and assembled by a team led by Dr. Robert Leighton.  Since radio astronomers built the telescope system, including the instruments and software, the CSO is one of the easiest telescopes to use for astronomical observations.   It is worthy of note that there are no telescope operators at the observatory, because observers know enough to run the telescope to take their scientific data (one has to have some technical background to operate the telescope).   Many key instruments are developed by graduate students and staff members at the observatory.  Major construction and operational funding for the CSO is provided by the National Science Foundation.

4. How many staff members work at the CSO?

Compared with other observatories at the mountain Mauna Kea, the CSO group is relatively small.  As of June 2005, 11 staff members and one volunteer are working at Hilo, about 13 staff members working at Caltech Pasadena campus.  The director of the observatory is Dr. Tom Phillips, professor at the Physics Department (part of the Division of Physics Mathematics, and Astronomy(PMA)), California Institute of Technology

5. Can I look through the telescope?

The CSO Leighton telescope does not have anything that anyone will look through. This is a radio telescope, so the observing wavelength of this telescope is much longer than optical wavelengths (see also FAQ #1 written above).   The human eye is not sensitive at this wavelength.  Instead, we have very sensitive detectors including submillimeter/millimeter cameras (for continuum observations) and heterodyne receivers (for spectroscopic observations).  One can take long integrations (exposures) using these instruments.  The ability of integrating over long period allows astronomers to detect very faint objects that are difficult to be detected.  The data acquired by the instruments will be stored on a computer and be analyzed in detail after observations are completed (read also FAQ #8). 
If you wish to explore the magnificent views of the beautiful night sky from Mauna Kea area, you may go to the Onizuka Center for International Astronomy Visitor Information Station (VIS), located at the mid level of the mountain.  They will provide you many kinds of telescopes which you can look through to explore the universe.

6. Can you observe in day-time as well as night-time?

As it  is a radio telescope, one can observe at any time during the night or day with the CSO Leighton telescope. However, typical observing operation occurs starting in the evening at about 7pm and ceases at about 7am.  When the observing weather is extremely good, observations are extended into daytime.  Daytime operations are restricted by Sun avoidance as we must keep direct Sunlight off of the collecting surface for safety reasons.  Other factors restricting daytime astronomical use of the telescope include our need to service instruments, mechanical running gear, and so forth. 

7.  Who uses the telescope?

The observatory is owned and operated by Caltech under a contract from the National Science Foundation.  About one third of the time at the CSO Leighton telescope is reserved for Caltech (including JPL) users.  One half of the time is for national and international observers, and the remainder is for users from the University of Hawai'i and the University of Texas at Austin.  Specific projects will be selected by Telescope Allocation Committees (so called TAC) at each institution, which meet twice a year, after two proposal semesters in May and October.  Astronomers apply to their local TAC, which decides if a proposal is scientifically feasible and has an impact in the fields.  The observing proposals submitted to the TACs will be ranked and a scheduler will allocate time according to the priorities and coordinates of targets.  If weather is not good enough on the assigned nights, one has to apply for telescope time again.
An important feature of the CSO is that it can provide a platform for new instruments being developed by some of our users.  For example, in recent years, the CSO has been hosting instruments being developed by researchers at Cardiff University, Cornell University, JPL(Jet Propulsion Laboratory), NASA Goddard, Northwestern University, Stanford University, University of Chicago, University of Colorado, University of Western Ontario, and so on. 

8. How often do astronomers use the telescope?

  Some projects require a lot of observing time, others require just a couple of nights.  On average, astronomers use the telescope only a few nights a year. Astronomers spend a long time (typically weeks or months) to prepare their observing runs.  This includes determining the priority and making backup plans for unpredictable weather.  Once the data have been obtained, a great deal of time will be spent on analysis.  It often takes months or even years to turn the raw data into scientific results.  Astronomers spend most of their time on this analysis, researching others' work, discussions with collaborators to fit results into a big picture, and describing the results in papers to publish.

9. Do you have open house?

Unfortunately no.  However, we join many local events in Hilo, such as Astroday, Onizuka Science Day, Journey through the Universe (Hilo HI) Family Science day, and so on. 

10. Do you have more explanations on your technical terms/acronyms written on your web pages?

For example, you may try to look for the terms or words in Astronomy Glossary compiled by NED (NASA/IPAC Extragalactic Database, at Caltech). ('Glossary' means a list of technical or special words, explaining their meanings. ) You can find quite a lot of web sites which provide you astronomy/physics glossary, through search engine web sites such as Google.

Go back to A Digest of Recent News and Scientific Results at the Caltech Submillimeter Observatory